The idea of ubiquitous computing is helpful to let people who benefit from the computer or other electronic devices see no device as they use it. People's natural activities can drive the applications executed as needed without explicit commands.
The first task to build a ubiquitous computing platform is to carry out an object tracking and recognition to acquire the activity status of a user. For example, in a digital home environment, the activity status can be any information on location, motion, gestures, voice, or face expression of the user. With the detection and analysis on user's activity status, the system can take corresponding actions without explicit operations on home devices.
A simple application scenario can be described as follows: 1) A TV set for example is in off status regardless of a user moving in and out the living room where the TV set is placed. 2) Once the user shows intention to watch the TV for example by sitting on the coach or standing still in front of the TV, the TV flashes (like blinking its eyes). 3) When the user waives to the TV with his hand a couple of times, the TV turns on. 4) The user can continue to operate the TV with his hand gestures or voice command. 5) When the user moves out of living room, the TV program is paused; and when the user moves back, the TV program is resumed.
Traditionally, Radio frequency identification (RFID) location determining system is used for user location detection. However it is still difficult to have the location detection because the obtained power strength is not always stable in a multipath indoor environment. In addition, video camera for tracking objects is common in the art. The image information of the object, such as location including the “real world” coordinates of the object, the “physical” location of the object, the “3D” coordinates of the object, the motion, the gesture and so on, is determined from the appearance of the object in the field of view of one or more cameras.
One simple hybrid location detection and object recognition method is as follows: each home user wears an active RFID tag transmitting radio signals to receivers inside home. A simple setup is to locate one RFID receiver on top of the electronic device to be controlled, such as TV. The tag can be attached on user's shoes or clothing. In addition, multiple video devices such as camera, video tracking device, are also arranged on the top of TV or at a specific place in the room.